Methods and apparatus for reducing buildup of deposits in semiconductor processing equipment

ABSTRACT

An apparatus for cleaning a gas tube includes an actuator and a plunger head attached to the actuator. The actuator is configured to reciprocate the plunger head along a longitudinal axis of the gas tube between a retracted position and an extended position and to rotate the plunger head from a first angular position to a second angular position. A method of cleaning a gas tube includes positioning a plunger head including a plurality of longitudinally extending tines in the gas tube, rotating the plunger head relative to a longitudinal axis of the gas tube, and scraping deposits from an interior surface of the gas tube using longitudinally extending edges of the tines.

RELATED APPLICATION

This application claims the benefit of and priority to U.S. Provisionalpatent application No. 60/730,537, filed Oct. 26, 2005, the disclosureof which is hereby incorporated herein by reference as if set forth inits entirety.

FIELD OF THE INVENTION

The present invention relates to semiconductor processing equipment,and, in particular, to methods and apparatus for processing wastecomponents generated in semiconductor processes.

BACKGROUND

Many semiconductor processes employ process gases containing reactantmaterials that are used to form and/or treat semiconductor materials.For example, chemical vapor deposition (CVD) processes typically employprocess gases to provide source materials for the growth and/orformation of thin layers of materials. Metal-organic CVD processes mayuse metal-organic process gases such as trimethyl gallium (TMG) andtrimethyl aluminum (TMA) as source gases for gallium and aluminum,respectively. Halides, such as BCl₃, and other materials, such as silane(SiH₄), may be used in CVD processes. Fluorine-based gases, such as NF₃and SF₆, may also be used in semiconductor processing operations.

In a CVD process, reactant gases are generally flowed across a growthsubstrate in a reaction chamber at a high temperature. The reactantgases may decompose near the growth substrate and deposit on thesubstrate to form a layer of material on the substrate. The CVD reactionmay generate a number of waste byproducts (components), such asunreacted components of reactant gases, carrier gases, reactionbyproducts, and/or other waste components. These waste components aretypically flushed from the reaction chamber through an exhaust tubeand/or vent during and/or after the semiconductor processing.

Many gases used in semiconductor processes, and the gaseous byproductsof the semiconductor processes, may pose health and/or environmentalhazards. Thus, exhaust gases generated by semiconductor processes aretypically treated to reduce such potential hazards. Exhaust gases may betreated, for example, using a thermal processing unit (TPU) that maythermally decompose exhaust gases. A TPU, which may beelectrically-fired and/or fuel-fired, may be configured to combustexhaust gases and scrub the combusted gases to reduce hazardous airpollutants.

Conventionally, a TPU is coupled to a semiconductor processing tool bymeans of a TPU inlet tube, which receives exhaust gases generated in thetool. Waste byproducts in the exhaust gases may build up as deposits inthe inlet tube, which may cause the inlet tube to become partiallyand/or completely blocked. It may be difficult and/or time-consuming toclean and/or replace an inlet tube of a TPU. Moreover, to clean and/orreplace an inlet tube of a TPU, it may be necessary to inactivate thesemiconductor processing equipment that uses the TPU, which may resultin significant expense and/or loss of equipment utilization.

In conventional systems, it is known to use a pneumatic piston to scrapebuilt-up waste deposits from the inside of a TPU inlet tube. Althoughsuch conventional approaches may reduce build-up of waste materials in aTPU inlet tube, such approaches have not been entirely successful, withthe result that it may frequently be necessary to manually clean a TPUinlet tube, even when such approaches are employed.

SUMMARY

Some embodiments of the invention provide an apparatus for cleaning agas tube having a longitudinal axis. The apparatus includes an actuatorand a plunger head attached to the actuator. The actuator is configuredto reciprocate the plunger head along the longitudinal axis between aretracted position and an extended position and to rotate the plungerhead from a first angular position to a second angular position. Atleast a portion of the plunger head is located within the gas tube whenthe plunger arm is in the extended position. In addition, at least aportion of the plunger head may be located within the outlet tube whenthe plunger arm is in the retracted position.

The actuator may be further configured to rotate the plunger head fromthe first angular position when the plunger head is in the retractedposition to the second angular position when the plunger head is in theextended position as the plunger head is moved from the retractedposition to the extended position.

In some embodiments, the actuator may be further configured to rotatethe plunger head from a first angular position to the second angularposition while the plunger head is in the extended position.

The apparatus may further include a gas coupling chamber coupled to thegas tube. A housing may be disposed on the gas coupling chamber oppositethe gas tube, and the actuator may be mounted in the housing. The gascoupling chamber may include a gas inlet spaced apart from the actuatorhousing and the gas tube.

The plunger head may include a support member and a plurality of tinesextending from the support member. Respective ones of the plurality oftines include a first portion extending radially away from alongitudinal axis extending through the support member andlongitudinally away from a coupling location on the axial member and asecond portion extending away from the first portion parallel to thelongitudinal axis.

The coupling location may include a mounting nut on the support member,and the first portions of the plurality of tines may extend from themounting nut.

The plurality of tines may be spaced evenly around the support memberrelative to the longitudinal axis by an angular spacing between adjacenttines, and the angular spacing between adjacent tines may be no morethan the angular spacing between the first angular position and thesecond angular position.

The second portions of the tines may be disposed at a radial distancefrom the longitudinal axis that is no greater than a radius of the gasoutlet tube.

In some embodiments, the second portions of the tines may be disposed ata radial distance from the longitudinal axis that is greater than theradius of the gas outlet tube, such that the second portions of thetines are biased against an interior of the gas outlet tube by the firstportions of the tines. The first portions of the tines may extendlongitudinally at an angle relative to the axial member that is selectedto provide substantially uniform scraping force to the gas tube whenbiased by the first portions during rotation from the first angularposition to the second angular position.

The actuator may include a plunger arm attached to the plunger head, theplunger arm having helical features thereon that are configured to causethe plunger head to rotate between the first angular position in theretracted position and the second angular position in the extendedposition.

The actuator may include a pneumatic cylinder having a cylindricalsleeve and a plunger arm attached to the plunger head and disposedwithin the cylindrical sleeve. The cylindrical sleeve may includehelical features that are configured to cause the plunger arm to rotatebetween the first angular position in the retracted position and thesecond angular position in the extended position.

Some embodiments of the invention provide a plunger head for cleaningsemiconductor processing equipment. The plunger head may include asupport member and a plurality of tines extending from a couplinglocation on the axial member. Respective ones of the plurality of tinesmay include a first portion extending radially away from a longitudinalaxis extending through the support member and longitudinally away from acoupling location on the axial member and a second portion extendingaway from the first portion parallel to the longitudinal axis.

The plunger head may further include a mounting nut on the axial member,and the first portions of the plurality of tines may extend from themounting nut. The plurality of tines may be spaced evenly around thesupport member relative to the longitudinal axis. In particularembodiments, the plurality of tines may include three tines that arespaced evenly around the axial member relative to the longitudinal axis.

Some embodiments of the invention provide methods of cleaning a gas tubeof a semiconductor processing equipment. The methods include positioninga plunger head including a plurality of longitudinally extending tinesin the gas tube, rotating the plunger head about a longitudinal axis ofthe gas tube, and scraping deposits from the gas tube usinglongitudinally extending edges of the plurality of longitudinallyextending tines. The methods may further include biasing thelongitudinally extending tines against the interior surface of the gastube.

The methods may further include reciprocating the plunger head into/outof the gas tube between a retracted position and an extended positionwhile rotating the plunger head.

In some embodiments, the plurality of longitudinally extending tines maybe spaced apart from one another by an angular spacing, and rotating theplunger head may include rotating the plunger head by an angulardistance that is greater than or about equal to the angular spacing asthe plunger head is reciprocated between the extended position and theretracted position.

In further embodiments, the plurality of longitudinally extending tinesmay be spaced apart from one another by an angular spacing, and rotatingthe plunger head may include rotating the plunger head by an angulardistance that is less than the angular spacing as the plunger head isreciprocated between the extended position and the retracted position.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate certain embodiment(s) of theinvention. In the drawings:

FIG. 1 is a schematic diagram illustrating a conventional exhaustcoupling apparatus;

FIG. 2 is a cutaway schematic diagram illustrating a conventionalexhaust coupling apparatus;

FIG. 3 is a schematic diagram illustrating a pneumatic cylinder andplunger according to some embodiments of the invention;

FIG. 4 is a schematic front view illustrating a plunger head accordingto some embodiments of the invention;

FIG. 5 is a perspective view illustrating a plunger head according tosome embodiments of the invention;

FIG. 6 is a schematic top view illustrating a plunger head according tosome embodiments of the invention;

FIG. 7 is a schematic side view illustrating a plunger head according tosome embodiments of the invention;

FIG. 8 is a cutaway schematic diagram illustrating an exhaust couplingapparatus according to some embodiments of the invention; and

FIGS. 9A-9B are schematic diagrams illustrating the operation of acleaning apparatus according to some embodiments of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present invention now will be described more fully hereinafter withreference to the accompanying drawings, in which embodiments of theinvention are shown. This invention should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of the invention to those skilled in the art.Like numbers refer to like elements throughout. Furthermore, the variouslayers and regions illustrated in the figures are illustratedschematically.

It will be understood that, although the terms “first,” “second,” etc.may be used herein to describe various elements, these elements shouldnot be limited by these terms. These terms are only used to distinguishone element from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of the present invention. Asused herein, the term “and/or” includes any and all combinations of oneor more of the associated listed items.

It will be understood that when an element such as a layer, region orsubstrate is referred to as being “on” or extending “onto” anotherelement, it can be directly on or extend directly onto the other elementor intervening elements may also be present. In contrast, when anelement is referred to as being “directly on” or extending “directlyonto” another element, there are no intervening elements present. Itwill also be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present.

Relative terms such as “below” or “above” or “upper” or “lower” or“horizontal” or “vertical” may be used herein to describe a relationshipof one element, layer or region to another element, layer or region asillustrated in the figures. It will be understood that these terms areintended to encompass different orientations of the device in additionto the orientation depicted in the figures.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”“comprising,” “includes” and/or “including” when used herein, specifythe presence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms used herein should be interpreted ashaving a meaning that is consistent with their meaning in the context ofthis specification and the relevant art and will not be interpreted inan idealized or overly formal sense unless expressly so defined herein.

Typically, an inlet tube of a TPU is coupled to an exhaust tube of asemiconductor processing tool, such as a CVD reactor. A conventionalexhaust coupling apparatus 20 is illustrated in FIG. 1. As showntherein, waste components that are output from a reaction chamber (notshown) of the semiconductor processing tool flow through an exhaust tube22 of the semiconductor processing tool into an exhaust coupling chamber26. The waste components flow from the exhaust coupling chamber 26 intoan inlet tube 28 of a TPU (not shown). In order to reduce build-up ofwaste material in the TPU inlet tube 28, a plunger housing 24 may beaffixed to and/or formed integrally with the exhaust coupling chamber 26opposite the TPU inlet tube 28 as shown.

The exhaust coupling apparatus 20 includes a conventional cleaningapparatus and is illustrated in FIG. 2. As shown therein, wastematerials 35 may build up within the TPU inlet tube 28 at or near aninterface of the TPU inlet tube 28 with the exhaust coupling chamber 26.If left unchecked, such waste materials 35 may clog the TPU inlet tube28, and may eventually choke off the tube 28 altogether.

In order to reduce build-up of waste materials 35 within the TPU inlettube 28, an actuator, such as a pneumatic and/or hydraulic cylinder 30,may be disposed within the plunger housing 24. A plunger arm 32 extendslongitudinally from the pneumatic cylinder 30 towards the TPU inlet tube28.

A plunger head 34 is affixed to an end of the plunger arm 32 thatextends away from the pneumatic cylinder 30. A conventional plunger head34 may include a metal spring, for example. The plunger arm 32 andplunger head 34 may reciprocated by the pneumatic cylinder 30 into andout of the TPU inlet tube 28 in a longitudinal direction (i.e. in adirection parallel to the TPU inlet tube 28). As the plunger head 34 iscycled longitudinally in and out of the TPU inlet tube 28, the plungerhead 34 may contact and may scrape waste materials 35 that are built-upon an inside surface of the TPU inlet tube 28, which may cause the wastematerials 35 to fall into the TPU inlet tube 28 so that they may beprocessed by the TPU. However, the longitudinal scraping action of aconventional apparatus may be insufficient to efficiently remove buildup of certain types of deposits.

A plunger assembly 50 according to some embodiments of the invention isillustrated in FIG. 3. The plunger assembly 50 includes an actuator 52,which may be a pneumatic and/or hydraulic cylinder having a fluidinlet/outlet 53 therein for receiving/expelling gas/fluid that may beused to pneumatically or hydraulically drive a plunger arm 54. It willbe appreciated that the actuator 52 may be implemented using anymechanism configured to reciprocate the plunger arm 54. Although in theillustrated embodiments the plunger arm 54 may be driven by pneumaticaction, it will be appreciated that the plunger arm 54 may be drivenmechanically instead of pneumatically or hydraulically, for example bymeans of an electric motor, a magnetic drive or the like, or by othermeans known to those skilled in the art. Accordingly, embodiments of theinvention are not limited to the use of pneumatic cylinders as theactuator. However, for purposes of description, the actuator 52 will bereferred to below as a pneumatic cylinder 52.

An optional connector 56 configured to receive a plunger head may bedisposed at a distal end of the plunger arm 54 located away from thepneumatic cylinder 52.

As the plunger arm 54 reciprocates into/out of the pneumatic cylinder52, the plunger arm 54 may pass through a cylindrical sleeve 55. Thecylindrical sleeve 55 may include therein one or more helical features,such as helical grooves and/or helical protrusions 57 a, that maycooperate with respective grooves, threads and/or protrusions on anouter surface of the plunger arm 54 to cause the plunger arm 54 torotate about a longitudinal axis 59 as it is driven into/out of thepneumatic cylinder 52. Alternatively or additionally, the plunger arm 54may include one or more helical features, such as helical grooves and/orhelical protrusions 57 b, on an outer surface thereof that may cooperatewith respective grooves, threads and/or protrusions on an inner surfaceof the cylindrical sleeve 55, to cause the plunger arm 54 to rotate in acircumferential direction 62 about the longitudinal axis 59 as it isdriven into/out of the pneumatic cylinder 52 in a longitudinal direction64. A plunger head may be detachably affixed to the optional connector56 and/or directly to the distal end of the plunger arm 54.

Instead of using helical grooves/protrusions, the plunger arm 54 may berotated about the longitudinal axis 59 by other means known to thoseskilled in the art, such as an electric motor, a magnetic drive and/orthe like, as it is reciprocated into/out of the pneumatic cylinder 52.

FIGS. 4-7 are schematic views illustrating a plunger head 40 accordingto some embodiments of the invention. As shown in FIGS. 4-7, the plungerhead 40 may include an axial member 42 extending along a central axis 45thereof. In the illustrated embodiments, the axial member 42 includes ametal tube. A mounting nut 44 may be affixed to the axial member 42, anda plurality of tines 48 a-48 c may be affixed to the mounting nut 44. Insome embodiments, the tines 48 a-48 c may be welded to the mounting nut44. However, the tines 48 a-48 c may be affixed to the mounting nut 44by any means known to those skilled in the art, such as, for example,using mechanical fasteners, adhesives, of the like. The tines 48 a-48 cmay extend away from the mounting nut 44.

It will be appreciated that the mounting nut 44 and the axial member 42may be provided as separate components and/or may be formed as anintegral component. It will be further appreciated that the mounting nut44 may be omitted altogether, in which case the tines 48 a-48 c may beaffixed directly to the axial member 42.

Each of the tines 48 a-48 c may include a first portion 46 that extendsradially and longitudinally away from the mounting nut 44, such that itis angled away from the central axis 45, and a second portion 47 thatruns generally parallel to the central axis 45 away from the firstportion 46. The first portion 46 may extend at an angle and/or lengthsuch that the second portion 47 may be spaced away from the central axis45 by a distance that is approximately equal to a radius of a tube, suchas a TPU inlet tube, in which the plunger head 40 is used. As shown inFIG. 7, the outer surfaces of the second portions 47 of the tines 48a-48 c may be spaced away from the central axis 45 by a distance r thatis slightly less than, equal to, or slightly greater than a radius of atube, such as a TPU inlet tube, in which the plunger head 40 is used. Itwill be appreciated that the tines 48 a-48 c need not actually touch theinner surface of the tube in order to reduce the build-up of deposits byan amount sufficient to permit the flow of gas through the tube. Forexample, in some cases, it may be sufficient for the head 40 to punchthrough material that has built up within the tube without necessarilyscraping off all of the material that has built up on the walls of thetube.

In addition to providing the second portions 47 at a desired spacedradial position, the first portions 46 may function as springs to biasthe second portions 47 against an interior surface of a tube, such as aTPU inlet tube, in which the plunger head 40 is used, particularly whenthe distance r is slightly greater than the radius of the receivingtube. The tines 48 a-48 c may be formed, for example, of stainlesssteel.

As noted above, the second portions 47 of the tines 48 a-48 c extend ina longitudinal direction substantially parallel to a central axis 45 ofthe plunger head 40. Thus, when the plunger head 40 is inserted into atube, such as a TPU inlet tube, and the plunger head is rotated aboutthe central axis 45, the tines 48 a-48 c may scrape against the interiorof the tube and/or deposits built up thereon in a circumferentialdirection, that is, in a direction that is perpendicular and/or obliqueto the longitudinal direction of the tube.

In the illustrated embodiments, the plunger head 40 includes three tines48 a-48 c spaced evenly about a central axis 45 of the plunger head 40at an angular spacing α of about 120°, as seen most clearly in FIG. 6.However, the plunger head 40 may include more or fewer tines than thethree tines illustrated. Moreover, the tines may be evenly and/orunevenly spaced around the plunger head 40.

As the plunger head 40 is reciprocated both longitudinally andcircumferentially about the central axis 45, the tines 48 a-c of theplunger head 40 may follow a generally helical path. Thus, thepunching/scraping action may proceed in a helical or spiraling pathrelative to the central axis 45. This may be contrasted to conventionalapproaches in which the scraping action is typically performed in alongitudinal direction that is parallel to both the tube being cleanedas well as to the direction of flow of exhaust gases in the tube.

FIG. 8 is a cutaway diagram illustrating a cleaning apparatus 60according to some embodiments of the invention. As shown therein, wastecomponents output from a reaction chamber flow through an inlet 25coupled to an exhaust tube 22 of the semiconductor processing equipmentinto an exhaust coupling chamber 26. The waste components flow from theexhaust coupling chamber 26 into an inlet tube 28 of a TPU (not shown).A plunger housing 24 is be affixed to and/or is formed integrally withthe exhaust coupling chamber 26 opposite the TPU inlet tube 28 as shown.

A pneumatic cylinder 52 (or the like as discussed above) may be disposedwithin the plunger housing 24. A plunger arm 54 extends longitudinallyfrom the pneumatic cylinder 52 towards the TPU inlet tube 28. A plungerhead 40 is affixed to an end of the plunger arm 54 that extends awayfrom the pneumatic cylinder 52. The plunger arm 54 and plunger head 40are driven by the pneumatic cylinder 52 into and out of the TPU inlettube 28 in a longitudinal direction (i.e. in a direction parallel to theTPU inlet tube 28). As the plunger arm 54 and plunger head 40 are drivenin a longitudinal direction 64 into/out of the TPU inlet tube 28, theplunger arm 54 and plunger head 40 may be rotated about a central axis45 in a circumferential direction 62 as described above.

As the plunger head 40 is cycled longitudinally in and out of the TPUinlet tube 28 and rotated about a central axis 45 thereof, the tines 48a-c of the plunger head 40 may scrape waste materials that may build upon an inside surface of the TPU inlet tube 28 in a scraping motion thatproceeds circumferentially around an interior surface of the inlet tube28 as the tines 48 a-c of the plunger head 40 travel in a helical pathrelative to the central axis 45. The scraping action of the tines 48 a-cmay be performed primarily by the outer surfaces and/or ridges of thesecond portions 47 of the tines 48 a-c, which extend in a longitudinaldirection substantially parallel with the central axis 45. Thepunching/scraping action of the plunger head 40 may cause built up wastematerials to fall into the TPU inlet tube 28 so that they may beprocessed by the TPU.

FIGS. 9A-9B are schematic diagrams illustrating the operation of aplunger assembly including a plunger arm and a plunger head according tosome embodiments of the invention. As illustrated in FIG. 9A, a plungerhead 40, which is disposed at the end of a plunger arm 54 that extendsfrom a pneumatic cylinder 52, is inserted into a tube, such as a TPUinlet tube 28. With the plunger arm 54 fully and/or partially retractedinto the pneumatic cylinder 52, the plunger head 40 may be positioned,in a retracted position, partially within the tube 28 such that at leasta length d of the second portions 47 of the tines 48 a-48 c remainsoutside the tube 28.

As illustrated in FIG. 9B, as the plunger arm 54 is extended from thepneumatic cylinder 52 by a distance d, the plunger head 40 is driveninto the tube 28 by the same distance to an extended position and isconcurrently rotated about a central axis thereof. In particular, theplunger head 40 may be rotated such that, when the plunger arm 54 hasbeen extended by at least a distance d, the plunger head has beenrotated by at least an angle sufficient to move a tine 48 b to anangular position previously occupied by an adjacent tine, such as tine48 a. Accordingly, the amount of angular rotation that may be performedfor a given insertion length may depend on the angular spacing α ofadjacent tines 48 to help provide that a desired circumference of thetube 28 is scraped in each cycle of the plunger arm 54 into/out of thecylinder 52.

In some embodiments, in order to help provide complete scrapingcoverage, the plunger head 40 may be rotated by an angle that is greaterthan the angular spacing of adjacent tines 48 in each cycle of theplunger arm 54 into/out of the cylinder 52. However, in someembodiments, the plunger head 40 may be rotated by an angle that is lessthan the angular spacing of adjacent tines 48, while still achieving areduction of waste deposits on the interior surface of the tube 28. Forexample, for an angular spacing α of 120° between adjacent tines 48, itmay be sufficient to rotate the plunger head 40 by an angle of onlyabout 90° as the head travels between a retracted position and anextended position.

The head 40 need not include tines 48, but may include ridges,protrusions or other scraping features/elements thereon. Also, theplunger head 40 need not be reciprocated in and out of the tube but maybe inserted into the tube and spun about the central axis. Thus, in someembodiments, the motion of the plunger head 40 may include onlyrotational motion and not longitudinal motion.

The rate of punching/scraping (e.g. in cycles per minute) may bedetermined by the type of actuator used. The punching/scraping proceduremay be performed often enough to reduce build up of deposits such thatthe exhaust tube does not become significantly blocked. For example, itmay be sufficient to cycle the head 40 one or more times every fiveminutes.

In the drawings and specification, there have been disclosed typicalembodiments of the invention and, although specific terms are employed,they are used in a generic and descriptive sense only and not forpurposes of limitation, the scope of the invention being set forth inthe following claims.

1. An apparatus for cleaning a gas tube having a longitudinal direction,the apparatus comprising: an actuator; and a plunger head attached tothe actuator, wherein the actuator is configured to reciprocate theplunger head along the longitudinal direction between a retractedposition and an extended position and to rotate the plunger head from afirst angular position to a second angular position; wherein at least aportion of the plunger head is located within the gas tube when theplunger head is in the extended position; and wherein the plunger headcomprises at least one tine including a portion that extends parallel tothe longitudinal direction when the plunger head is positioned withinthe gas tube, wherein the plunger head comprises: a support member; anda plurality of tines including the at least one tine extending from thesupport member, respective ones of the plurality of tines including afirst portion extending radially away from a longitudinal axis extendingthrough the support member and longitudinally away from a couplinglocation on the support member and a second portion extending away fromthe first portion parallel to the longitudinal axis.
 2. The apparatus ofclaim 1, wherein the actuator is configured to rotate the plunger headfrom the first angular position when the plunger head is in theretracted position to the second angular position when the plunger headis in the extended position as the plunger head is moved from theretracted position to the extended position.
 3. The apparatus of claim1, wherein the actuator is configured to rotate the plunger head from afirst angular position to the second angular position while the plungerhead is in the extended position.
 4. The apparatus of claim 1, whereinthat at least a portion of the plunger head is located within the gastube when the plunger head is in the retracted position.
 5. Theapparatus of claim 1, further comprising: a gas coupling chamber coupledto the gas tube; and a housing on the gas coupling chamber opposite thegas tube; wherein the actuator is mounted within the housing; andwherein the gas coupling chamber includes a gas inlet spaced apart fromthe actuator housing and the gas tube.
 6. The apparatus of claim 1,wherein the coupling location comprises: a mounting nut on the supportmember, wherein the first portions of the plurality of tines extend fromthe mounting nut.
 7. The apparatus of claim 1, wherein the plurality oftines are spaced evenly around the support member relative to thelongitudinal axis by an angular spacing between adjacent tines, andwherein the angular spacing between adjacent tines is no more than theangular spacing between the first angular position and the secondangular position.
 8. The apparatus of claim 1, wherein the secondportions of the tines are disposed at a radial distance from thelongitudinal axis that is no greater than a radius of the gas tube. 9.The apparatus of claim 1, wherein the second portions of the tines aredisposed at a radial distance from the longitudinal axis that is greaterthan the radius of the gas tube, such that the second portions of thetines are biased against an interior of the gas tube by the firstportions of the tines.
 10. The apparatus of claim 9, wherein the firstportions of the tines extend longitudinally at an angle relative to theaxial member that is selected to provide substantially uniform scrapingforce to the gas tube when biased by the first portions during rotationfrom the first angular position to the second angular position.
 11. Theapparatus of claim 1, wherein the actuator further comprises a plungerarm and wherein the plunger head is attached to the plunger arm; andwherein the plunger arm includes helical features thereon that areconfigured to cause the plunger arm to rotate between the first angularposition when the plunger head is in the retracted position and thesecond angular position when the plunger head is in the extendedposition.
 12. The apparatus of claim 1, wherein the actuator comprises apneumatic cylinder including a cylindrical sleeve and a plunger armdisposed within the cylindrical sleeve, wherein the plunger head isattached to the plunger arm, and wherein the cylindrical sleeve includeshelical features that are configured to cause the plunger arm to rotatebetween the first angular position when the plunger head is in theretracted position and the second angular position when the plunger headis in the extended position.